Photodynamic Therapy in Acne Vulgaris: A Systematic Review.

Acne is a multifactorial disorder of the pilosebaceous unit. Photodynamic therapy (PDT) is an energy-based treatment shown to be safe in acne vulgaris, although the mechanism of action of PDT in acne is incompletely understood. This review summarizes the clinical features of and treatment efficacy in acne patients treated with PDT. A systematic review of Medline, Embase, and the Cochrane Database of Systematic Reviews was conducted. Title, abstract, full-text screening, and data extraction were completed using Covidence. Studies reporting the use of PDT in patients with acne were included while clinical features and treatment responses were extracted. Treatment outcomes were scored as complete response, partial response, and no response. After screening a total of 1122 studies, 82 studies met the inclusion criteria, representing 56 prospective studies, 25 randomized controlled trials, and 1 retrospective study. Results representing 4340 patients with acne (mean age 24.4 years; 52% females) treated with PDT are summarized. Overall, 2154 (50%) participants underwent aminolevulinic acid PDT, 452 (10%) participants underwent methyl aminolevulinate PDT, 28 (<1%) participants underwent daylight PDT, and 1706 (39%) underwent other modalities of PDT. The average follow-up period after study completion was 3 months, ranging from 2 weeks to 13 months. A partial response was observed in treated patients with outcome measures including clinical response, lesion count, pain, recurrence, and patient satisfaction. This systematic review provides preliminary data summarizing the clinical features and treatment efficacy in patients with acne treated with PDT. Our results suggest a partial clinical response when using PDT to manage acne. Future studies should focus on standardizing study protocols and drawing direct comparisons between PDT and other modalities for acne treatment.